1. Field of the Invention
The present invention relates to a bistable bidirectional switch, that is, a switch capable of being turned on for several halfwaves of the A.C. voltage applied thereto, after a single control pulse. This bistable switch can then be turned off by application of a new pulse and remain off until it receives a new turn-on pulse.
2. Discussion of the Related Art
A first category of bidirectional switches is formed of triac-type switches or other bidirectional switches corresponding to thyristor associations. A common feature of these components is that they are turned on in a given halfwave by a pulse, and then automatically turn off when the current flowing therethrough falls under a determined threshold, generally called the hold current iH. Then, to turn such bidirectional switches back on, a pulse must be applied again upon each halfwave during which the component is desired to be on. Thus, such switches are not bistable.
Another category of bidirectional switches is formed of components of MOS or bipolar transistor type, which turn on when a signal is applied to their control terminal, but for which this control order must be continuously maintained for the component to remain on. Such transistor type components are not controllable with pulses.
In prior art, circuits associating semiconductor components and passive components in circuits enabling obtaining a pulse-controlled bistable bidirectional switch have been provided. However, such circuits are relatively complex and generally require association of several semiconductor components and of several passive components.